Chemical dilution

Question

Calculate the molarity of an H3PO4 solution prepared as follows: 5.00 mL of 10.0 M phosphoric acid is diluted to 250.0 mL in a volumetric flask, and from this flask 25.00 mL of this solution is diluted to 500.0 mL in another flask.

Answer 1

First dilution:

(5 ml)(10 M) = (250 ml)(x M)

x = 0.200 M

Second dilution:

(25 ml)(0.2 M) = (500 ml)(x M)

x = 0.0100 M <—Answer